Libraries are involved with patron's personal information, we all know that. We know who has what book checked out, and in many system there is a record of who has read what, used which computer, etc. Even when there are no physical records, this information can still exist in the form of logs, computer related information that is carried over for a period of time (cookies, etc.), and when books are checked out of a State libraries the records may exist outside the library where the materials were accessed even if that library does not keep records itself once the materials have been returned. It's just a fact of life.
There are laws in place to protect us, the public, from abuse of those in power when it comes to these records. And, while they are certainly not perfect, from from so since 2001, they are still the law, and this is a land of law and order based on those laws - or so we are told. In certain circumstances, people in positions of authority know that if they use their influence to coerce members of the public to abandon their rights, they will often get compliance despite their request being illegal. It happens all the time.